the effect of carbon content of the mechanical properties - McMaster ...

M.A.Sc. Thesis – E. E. Yang McMaster – Materials Science & Engineering
true stress (MPa)
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4.4 Fracture Analysis
0
Unloading Loop at 20%
Elastic Unloading Line (no offset)
Elastic Unloading Line (0.01% offset)
0.192 0.194 0.196
true strain
0.198 0.200
Figure 4.3 Bauschinger Unloading Loop Behaviour
(4.3)
Fracture analysis was performed to gain a better understanding of the effect of the
damage processes and fracture modes as a function of alloy composition. The fracture
surface was viewed under the SEM. The dimensions of the fracture surface were also
measured using both OM and SEM in order to calculate an approximate fracture stress
and strain. A sample fracture surface is seen in Figure 4.4 with the area calculated using
North Eclipse v. 6.0 imaging software. By taking the initial area (A0) and calculating the
final area (Af), with the load at fracture (Lf), a true fracture strain (εf) and true fracture
stress (σf) can be calculated from Equation 4.4 and Equation 4.5.
R
F
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